Herbicides are utilized in a necessary amount of diluted solution when applied. There are situations in which extra amounts are left over. There are also situations in which the applied herbicide, after its application for awhile, remains in the soil or plant residue. Originally, given that the safety of such herbicides has been checked, such small amounts of left-over solutions or residues presented small effects to the environment or to the crops cultivated thereafter. However, if there is a method in which the contained herbicidal compound is converted to one of lower herbicidal activity, then for example there can be conducted treatments to inactivate the left-over solutions or residues described above as needed.
Further, in the case of using the herbicide, there were situations in which it was difficult to distinguish cultivated plants from weeds of allied species to selectively control only weeds. Then, there is a desire to develop a new method for conferring herbicidal resistance to a target plant.